1. Field of the Invention
The present invention relates to a method and an apparatus of preventing warp of a skid panel.
2. Description of the Related Art
A skid panel is a precast pavement plate attached with a lot of wear resistance material pieces of porcelain tiles, basalt tiles or the like on its surface. It is used as a floor plate laid on a road face of a test course or the like for a braking test of an automobile. According to such a skid panel, there must be no warp or distortion in a longitudinal direction of laying the panel.
A skid panel is fabricated by alignedly laying porcelain tiles on a bottom face in a mold and feeding concrete into the mold and integrating the porcelain tiles with the concrete. According to such a skid panel, in feeding and curing the concrete, the concrete shrinks and in the meantime, the porcelain tiles do not shrink and therefore, the skid panel is warped such that a face thereof almost covered with many tile pieces constitutes a protruded face. The warp is harmful to the braking test and accordingly, an amount of the warp needs to be nullified. Conventionally, there has been no universal technology to minimize the warp amount of such a skid panel. In order to reduce the warp of the skid panels, skilled persons in the art have been tried to find adequate proportioning of concrete materials, proper dimensions of a panel, a shape and dimensions of a mold and a method of appropriate concrete curing by their experiences and perceptions.
The invention has been carried out in view of the above-described circumstances in which actual warp amounts and calculated warp amounts under respective fabrication conditions of skid panels, are verified, based on which a method and an apparatus of preventing warp of a skid panel having high reproducibility has been developed. It is an object of the invention to provide a method and an apparatus of preventing warp of a skid panel.
The invention has been carried out in order to achieve the above-described object and according to an aspect of the invention, there is provided a method of preventing warp of a skid panel, comprising:
calculating predictively a warp amount of a skid panel from a shrinkage strain, a shrinkage force and upper and lower edge stresses of concrete,
deforming a mold of the skid panel with a reverse camber corresponding to the above calculated warp amount so that the final warp amount after aging is nullified,
laying in rows porcelain tiles or basalt tiles on a bottom of the mold, and
depositing concrete into the mold to fabricate the skid panel in a shape bent reversely in a longitudinal direction of the skid panel.
In the present invention, a skid panel is fabricated in a shape having a reverse camber in a longitudinal direction of the skid panel such that the warp amount is finally nullified.
According to another aspect of the invention capable of preferably implementing the above-described invented method, there is provided an apparatus of preventing warp of a skid panel, comprising:
a bottom plate having a pattern for aligning tiles on the surface,
a side plates surrounding the bottom plate, and
a tensioning device for providing a camber in a circular arc shape at a bottom plate of a mold of the skid panel along a longitudinal direction of the mold.
A skid panel is a concrete slab in a flat plate shape having a thickness of 100 through 160 mm, a width of about 2 m and a length of about 6 m and the concrete slab is attached on the upper face with porcelain tiles or basalt tiles having a thickness of about 15 mm. The skid panel is a precast concrete product fabricated by spreading porcelain tiles or basalt tiles in rows on a bottom in a mold and feeding concrete thereon.